Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A 'jumping gene's' preferred targets may influence genome evolution

07.09.2011
The human genome shares several peculiarities with the DNA of just about every other plant and animal. Our genetic blueprint contains numerous entities known as transposons, or "jumping genes," which have the ability to move from place to place on the chromosomes within a cell.

An astounding 50% of human DNA comprises both active transposon elements and the decaying remains of former transposons that were active thousands to millions of years ago before becoming damaged and immobile.

If all of this mobile and formerly mobile DNA were not mysterious enough, every time a plant, animal or human cell prepares to divide, the chromosome regions richest in transposon-derived sequences, even elements long deceased, are among the last to duplicate. The reason for their delayed duplication, if there is one, has eluded biologists for more than 50 years.

New research led by Carnegie's Allan Spradling and published online this week by Proceedings of the National Academy of Sciences provides potential insight into both these enigmas.

The scientists used the fruit fly, Drosophila melanogaster, one of the premier "model" organisms for studying genome structure and gene function. They focused on one particular transposon, called the P element, which has an unsurpassed ability to move that has stimulated its widespread use by Drosophila researchers.

Remarkably, P elements have only been present in Drosophila melanogaster for about 80 years, at which time they were acquired from the genome of a distantly related fruit fly species by an unknown process. P elements remain highly "infective" today. Adding just one copy to the genome of one fly causes all the flies in a laboratory population with which it breeds to acquire 30 to 50 P elements within a few generations. The original goal of the Spradling team's research was not to understand how transposons spread or genomes evolve, but something much simpler: To learn why P elements insert at some locations in the genome but not in others.

Spradling and his colleagues, who oversee the NIH-funded Drosophila "Gene Disruption Project" used a database containing more than 50,000 genomic sites where P elements have inserted. They built this exceptional database over the last 20 years.

P elements insert into DNA very selectively. Nearly 40% of new jumps occur within just 300 genes and always near the beginning of the gene. But the genes seemed to have nothing in common. When these sites were compared to data about the Drosophila genome, particularly recent studies of Drosophila genome duplication, the answer became clear. What many P insertion sites share in common is an ability to function as starting sites or "origins" for DNA duplication. This association between P elements and the machinery of genome duplication suggested that they can coordinate their movement with DNA replication.

Spradling and his team propose that P elements—and likely other transposons as well—use a replication connection to spread more rapidly through genomes. These elements would only transpose after replicating, and then preferentially insert themselves into portions of DNA that have not yet become activated. This would allow them to duplicate twice rather than just once during the genome duplication cycle.

If the elements get a late start, however, only the last segments of the chromosome to duplicate will be left for their second duplication. This explains tendency of such regions to be transposon-rich. However, the researchers found that two other Drosophila transposons, known as piggyBac and Minos, do not insert at replication origins, so this mechanism is far from universal. Furthermore, Spradling cautioned that it is particularly difficult to experimentally test hypotheses about evolution.

"By gaining insight into one specific transposon's movements, we may have begun to glimpse mechanisms that have profoundly influenced genome evolution for nearly all animals" Spradling commented.

Spradling's co-authors on the paper are Hugo Bellen of Baylor College of Medicine and Roger Hoskins of Lawrence Berkeley National Laboratory.

Funding for this research was provided in part by the National Institutes of Health.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

Allan Spradling | EurekAlert!
Further information:
http://carnegiescience.edu

More articles from Life Sciences:

nachricht Are there sustainable solutions in dealing with dwindling phosphorus resources?
16.10.2017 | Leibniz-Institut für Nutzierbiologie (FBN)

nachricht Strange undertakings: ant queens bury dead to prevent disease
13.10.2017 | Institute of Science and Technology Austria

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

Im Focus: Small collisions make big impact on Mercury's thin atmosphere

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

Conference Week RRR2017 on Renewable Resources from Wet and Rewetted Peatlands

28.09.2017 | Event News

 
Latest News

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017 | Physics and Astronomy

The melting ice makes the sea around Greenland less saline

16.10.2017 | Earth Sciences

On the generation of solar spicules and Alfvenic waves

16.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>